As one example of systems for causing a chemical reaction to occur in a minute space, there has been known a microchemical system. The microchemical system performs mixture, reaction, separation, extraction and detection of a sample in a minute channel formed in a small glass substrate. A sample used in such a microchemical system is generally very small in amount, which requires a high sensitivity detection device for detecting the sample.
When fluorescence is particularly measured using an optical device as a detection device, a fluorescence measurement area is small, so that a higher sensitivity optical device is required. As a method of detecting fluorescence with a high sensitivity, there has been known a laser-induced fluorescence analysis. As an optical device using the laser-induced fluorescence analysis, there is disclosed a fluorescence analysis device including a light source, an optical multiplexer/demultiplexer, a detector and an optical fiber connecting these components together (refer to, for example, Japanese Laid-Open Patent Publication (Kokai) No. 2005-30830).
Incidentally, since the wavelength of excitation light which is used for generating fluorescence varies with a sample to be measured, a laser oscillator is not always used as a light source, for this reason, a light emitting diode (hereinafter, simply referred to as “LED”) is generally used as a light source which is capable of outputting a wavelength at which laser does not oscillate.
However, a conventional fluorescence analysis device has a problem that excitation light with which a sample is irradiated from a light source leaks into the detector to increase background at the time of detecting fluorescence, decreasing sensitivity of detecting fluorescence.
As a microchemical system has progressed, a sample to be used becomes smaller in amount, so that the abovementioned problem may become more conspicuous.
The present invention has been made in view of the above problem. The object of the present invention is to provide a fluorescence detection device capable of detecting fluorescence with a high sensitivity even if a sample generating fluorescence is small in amount.